IPv4 protocol is a widely deployed Internet protocol at present. However, with the rapid development of the Internet, design deficiencies of the IPv4 have become increasingly apparent, for example, the address space is insufficient, the number of table entries in a routing table maintained by a backbone router is too large to perform automatic configuration and re-addressing, and a security problem is too difficult to solve. IPv6, as a future alternative protocol of IPv4, has advantages such as a sufficient address space, a high routing efficiency, a high security and is easy to configure and extend, and also supports a mobility feature.
At present, a large number of networks are IPv4 networks, while with the deployment of the IPv6 protocol, there is a long-term transition stage in which the IPv4 and the IPv6 coexist. Dual-stack technology is effectively applied in the transition from the IPv4 to the IPv6, in which a node in the network simultaneously supports both IPv4 and IPv6 protocol stacks, different protocol stacks are selected for a source node based on different target nodes, and a network device selects different protocol stacks to perform processing and forwarding based on different protocol types for messages.
With the popularization of the computer (PC) and the rapid development of the communications service, the PC as well as communications has been already extensively applied in every aspect of people's life. It will bring a great convenience by applying a wireless terminal device on a PC, therefore a fixed network service, which has a relatively slow speed and is complicated to mount and maintain, is bound to be replaced by the wireless terminal device having a large development space in the following several years. There will be a general trend to simultaneously access the wireless terminal device into both the IPv4 and IPv6 networks.
At present, a wireless network operator has no uniform standard to support the IPv6 and there are various ways to implement IPv4 and IPv6 dual-stack network. This requires an attempting and fall-back mechanism for the wireless terminal device when it is accessed into the network. A general means based on the protocol is that: the wireless terminal device attempts to send an IPv4v6 single packet data protocol (PDP) activation request to establish a dual-stack connection firstly; if the attempt fails, the wireless terminal device falls back and attempts to send an IPv4 PDP activation request and an IPv6 PDP activation request to establish the dual-stack connection; if the attempt fails, then the wireless terminal device attempts to establish a single-stack connection. By such a means, it is relatively slow to establish the connection, and thus affecting the speed of network connection for a user.